#include <stdarg.h>
#include <errno.h>
#include "apue.h"

static void err_doit(int, const char *, va_list);

char *pname = NULL; /*caller can set this from argv[0]*/

/* Nonfatal error related to a system call.
 * Print a message and return. */

void err_ret(const char *fmt, ...){
	va_list ap;
	va_start(ap, fmt);
	err_doit(1, fmt, ap);
	va_end(ap);
	return;
}

/* Fatal error related to a system call.
 * Print a message and terminate. */
void err_sys(const char *fmt, ...){
	va_list ap;
	va_start(ap, fmt);
	err_doit(1, fmt, ap);
	va_end(ap);
	exit(1);
}

/* Fatal error related to a system call.
 * Print a message, dump core, and terminate. */

void err_dump(const char *fmt, ...){
	va_list ap;
	va_start(ap, fmt);
	err_doit(1, fmt, ap);
	va_end(ap);
	abort();	/* dump core and terminate */
	exit(1);	/* shouldn't get here */
}

/* Nonfatal error unrelated to a system call.
 * Print a message and return. */
void err_msg(const char *fmt, ...){
	va_list ap;
	va_start(ap, fmt);
	err_doit(0, fmt, ap);
	va_end(ap);
	return;
}

/* Fatal error unrelated to a system call.
 * Print a message and terminate. */
void err_quit(const char *fmt, ...){
	va_list ap;
	va_start(ap, fmt);
	err_doit(0, fmt, ap);
	va_end(ap);
	exit(1);
}

/* Print a message and return to caller.
 * Caller specifies "errnoflag". */
static void err_doit(int errnoflag, const char *fmt, va_list ap){
	int errno_save;
	char buf[MAXLINE];
	errno_save = errno; /* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), "%s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);	/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(NULL);	/* flushes all stdio output streams */
	return;
}
